1. Field of the Invention
The present invention relates generally to tape feeders for chip mounters, and more particularly to a tape feeder for chip mounters which allows a carrier tape loaded with semiconductor chips to be fed by a rectilinear moving unit, thus allowing the carrier tape to be precisely fed, and preventing the chips from being turned over and removed from the carrier tape while a vinyl cover is discharged and thereby minimizing a malfunction when the chips are picked. Therefore operational reliability is maximized, in addition to reducing the number of elements and the volume of the tape feeder.
2. Description of the Related Art
Generally, an electronic part mounter, that is, a chip mounter is a device that picks up electronic parts (semiconductor chips) via a vacuum lifting method by a nozzle of a head which picks and places the electronic parts fed by a feeder, and then mounts the electronic parts on a board.
There have been disclosed various kinds of feeders, including a tape feeder, a chip feeder, a tray feeder, etc. The present invention relates to the tape feeder which is capable of feeding a large number of chips at a high rate.
A carrier tape is applied to the tape feeder. Because the semiconductor chips received in the carrier tape have a very small size, it is difficult to pick up the semiconductor chips one by one. Further, it is difficult to treat the semiconductor chips received in the carrier tape, because the semiconductor chips are likely to contamination by foreign materials, such as dust, and a probability of loss is high.
Thus, the carrier tape 10 which has been commonly used is constructed as shown in FIG. 1. That is, the semiconductor chips (S.C) are received in receiving spaces 30 which are provided on a paper tape 20 at regular pitches, and then are sealed by a vinyl cover 40 to cover the receiving spaces 30 having the semiconductor chips. A plurality of feeding holes 50 are bored in the paper tape 20 to be arranged at regular intervals along a side of the paper tape 20.
The carrier tape 10 moves by a predetermined pitch while the feeding holes 50 of the carrier tape 10 being locked by the tape feeder mounted to the chip mounter. While the carrier tape 10 moves, the vinyl cover 40 is separated from the paper tape 20, so that the receiving spaces 30 are exposed. Thereafter, the semiconductor chips of the exposed receiving spaces 30 are picked up by the nozzle of the chip mounter.
However, the conventional tape feeder is constructed so that the carrier tape is fed by a predetermined pitch, by rotating a sprocket wheel and a ratchet in a certain direction while the feeding holes of the carrier tape are locked by a gear of the sprocket wheel.
Since the tape feeder is fed along segments of a circle divided at regular intervals, rotating tolerances are cumulated when the carrier tape is fed to some extent by the rotation of the sprocket wheel. In this case, the semiconductor chips are not precisely fed to target positions and thereby the feeding operation must be set again, therefore deteriorating workability and causing the production of bad products due to a malfunction when the semiconductor chips are picked up.
Further, the volume of the feeder is increased due to a complicated construction, so that it is impossible to realize a slim construction, thus having a low workability.